src/bin/lttng-sessiond/agent.c

   1 /*
   2  * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <assert.h>
  20 #include <urcu/uatomic.h>
  21
  22 #include <common/common.h>
  23 #include <common/sessiond-comm/agent.h>
  24
  25 #include <common/compat/endian.h>
  26
  27 #include "agent.h"
  28 #include "ust-app.h"
  29 #include "utils.h"
  30 #include "error.h"
  31
  32 #define AGENT_RET_CODE_INDEX(code) (code - AGENT_RET_CODE_SUCCESS)
  33
  34 /*
  35  * Human readable agent return code.
  36  */
  37 static const char *error_string_array[] = {
  38         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_SUCCESS) ] = "Success",
  39         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_INVALID) ] = "Invalid command",
  40         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_UNKNOWN_NAME) ] = "Unknown logger name",
  41
  42         /* Last element */
  43         [ AGENT_RET_CODE_INDEX(AGENT_RET_CODE_NR) ] = "Unknown code",
  44 };
  45
  46 static
  47 void log_reply_code(uint32_t in_reply_ret_code)
  48 {
  49         int level = PRINT_DBG3;
  50         /*
  51          * reply_ret_code and in_reply_ret_code are kept separate to have a
  52          * sanitized value (used to retrieve the human readable string) and the
  53          * original value which is logged as-is.
  54          */
  55         uint32_t reply_ret_code = in_reply_ret_code;
  56
  57         if (reply_ret_code < AGENT_RET_CODE_SUCCESS ||
  58                         reply_ret_code >= AGENT_RET_CODE_NR) {
  59                 reply_ret_code = AGENT_RET_CODE_NR;
  60                 level = PRINT_ERR;
  61         }
  62
  63         LOG(level, "Agent replied with retcode: %s (%"PRIu32")",
  64                         error_string_array[AGENT_RET_CODE_INDEX(
  65                         reply_ret_code)],
  66                         in_reply_ret_code);
  67 }
  68
  69 /*
  70  * Match function for the events hash table lookup by name.
  71  */
  72 static int ht_match_event_by_name(struct cds_lfht_node *node,
  73                 const void *_key)
  74 {
  75         struct agent_event *event;
  76         const struct agent_ht_key *key;
  77
  78         assert(node);
  79         assert(_key);
  80
  81         event = caa_container_of(node, struct agent_event, node.node);
  82         key = _key;
  83
  84         /* Match 1 elements of the key: name. */
  85
  86         /* Event name */
  87         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
  88                 goto no_match;
  89         }
  90         /* Match. */
  91         return 1;
  92
  93 no_match:
  94         return 0;
  95 }
  96
  97 /*
  98  * Match function for the events hash table lookup by name and loglevel.
  99  */
 100 static int ht_match_event(struct cds_lfht_node *node,
 101                 const void *_key)
 102 {
 103         struct agent_event *event;
 104         const struct agent_ht_key *key;
 105         int ll_match;
 106
 107         assert(node);
 108         assert(_key);
 109
 110         event = caa_container_of(node, struct agent_event, node.node);
 111         key = _key;
 112
 113         /* Match 2 elements of the key: name and loglevel. */
 114
 115         /* Event name */
 116         if (strncmp(event->name, key->name, sizeof(event->name)) != 0) {
 117                 goto no_match;
 118         }
 119
 120         /* Event loglevel value and type. */
 121         ll_match = loglevels_match(event->loglevel_type,
 122                 event->loglevel_value, key->loglevel_type,
 123                 key->loglevel_value, LTTNG_EVENT_LOGLEVEL_ALL);
 124
 125         if (!ll_match) {
 126                 goto no_match;
 127         }
 128
 129         /* Filter expression */
 130         if (strncmp(event->filter_expression, key->filter_expression,
 131                         strlen(event->filter_expression)) != 0) {
 132                 goto no_match;
 133         }
 134
 135         return 1;
 136
 137 no_match:
 138         return 0;
 139 }
 140
 141 /*
 142  * Add unique agent event based on the event name and loglevel.
 143  */
 144 static void add_unique_agent_event(struct lttng_ht *ht,
 145                 struct agent_event *event)
 146 {
 147         struct cds_lfht_node *node_ptr;
 148         struct agent_ht_key key;
 149
 150         assert(ht);
 151         assert(ht->ht);
 152         assert(event);
 153
 154         key.name = event->name;
 155         key.loglevel_value = event->loglevel_value;
 156         key.loglevel_type = event->loglevel_type;
 157         key.filter_expression = event->filter_expression;
 158
 159         node_ptr = cds_lfht_add_unique(ht->ht,
 160                         ht->hash_fct(event->node.key, lttng_ht_seed),
 161                         ht_match_event, &key, &event->node.node);
 162         assert(node_ptr == &event->node.node);
 163 }
 164
 165 /*
 166  * URCU delayed agent event reclaim.
 167  */
 168 static void destroy_event_agent_rcu(struct rcu_head *head)
 169 {
 170         struct lttng_ht_node_str *node =
 171                 caa_container_of(head, struct lttng_ht_node_str, head);
 172         struct agent_event *event =
 173                 caa_container_of(node, struct agent_event, node);
 174
 175         agent_destroy_event(event);
 176 }
 177
 178 /*
 179  * URCU delayed agent app reclaim.
 180  */
 181 static void destroy_app_agent_rcu(struct rcu_head *head)
 182 {
 183         struct lttng_ht_node_ulong *node =
 184                 caa_container_of(head, struct lttng_ht_node_ulong, head);
 185         struct agent_app *app =
 186                 caa_container_of(node, struct agent_app, node);
 187
 188         free(app);
 189 }
 190
 191 /*
 192  * Communication with the agent. Send the message header to the given socket in
 193  * big endian.
 194  *
 195  * Return 0 on success or else a negative errno message of sendmsg() op.
 196  */
 197 static int send_header(struct lttcomm_sock *sock, uint64_t data_size,
 198                 uint32_t cmd, uint32_t cmd_version)
 199 {
 200         int ret;
 201         ssize_t size;
 202         struct lttcomm_agent_hdr msg;
 203
 204         assert(sock);
 205
 206         memset(&msg, 0, sizeof(msg));
 207         msg.data_size = htobe64(data_size);
 208         msg.cmd = htobe32(cmd);
 209         msg.cmd_version = htobe32(cmd_version);
 210
 211         size = sock->ops->sendmsg(sock, &msg, sizeof(msg), 0);
 212         if (size < sizeof(msg)) {
 213                 ret = -errno;
 214                 goto error;
 215         }
 216         ret = 0;
 217
 218 error:
 219         return ret;
 220 }
 221
 222 /*
 223  * Communication call with the agent. Send the payload to the given socket. The
 224  * header MUST be sent prior to this call.
 225  *
 226  * Return 0 on success or else a negative errno value of sendmsg() op.
 227  */
 228 static int send_payload(struct lttcomm_sock *sock, void *data,
 229                 size_t size)
 230 {
 231         int ret;
 232         ssize_t len;
 233
 234         assert(sock);
 235         assert(data);
 236
 237         len = sock->ops->sendmsg(sock, data, size, 0);
 238         if (len < size) {
 239                 ret = -errno;
 240                 goto error;
 241         }
 242         ret = 0;
 243
 244 error:
 245         return ret;
 246 }
 247
 248 /*
 249  * Communication call with the agent. Receive reply from the agent using the
 250  * given socket.
 251  *
 252  * Return 0 on success or else a negative errno value from recvmsg() op.
 253  */
 254 static int recv_reply(struct lttcomm_sock *sock, void *buf, size_t size)
 255 {
 256         int ret;
 257         ssize_t len;
 258
 259         assert(sock);
 260         assert(buf);
 261
 262         len = sock->ops->recvmsg(sock, buf, size, 0);
 263         if (len < size) {
 264                 ret = -errno;
 265                 goto error;
 266         }
 267         ret = 0;
 268
 269 error:
 270         return ret;
 271 }
 272
 273 /*
 274  * Internal event listing for a given app. Populate events.
 275  *
 276  * Return number of element in the list or else a negative LTTNG_ERR* code.
 277  * On success, the caller is responsible for freeing the memory
 278  * allocated for "events".
 279  */
 280 static ssize_t list_events(struct agent_app *app, struct lttng_event **events)
 281 {
 282         int ret, i, len = 0, offset = 0;
 283         uint32_t nb_event;
 284         size_t data_size;
 285         uint32_t reply_ret_code;
 286         struct lttng_event *tmp_events = NULL;
 287         struct lttcomm_agent_list_reply *reply = NULL;
 288         struct lttcomm_agent_list_reply_hdr reply_hdr;
 289
 290         assert(app);
 291         assert(app->sock);
 292         assert(events);
 293
 294         DBG2("Agent listing events for app pid: %d and socket %d", app->pid,
 295                         app->sock->fd);
 296
 297         ret = send_header(app->sock, 0, AGENT_CMD_LIST, 0);
 298         if (ret < 0) {
 299                 goto error_io;
 300         }
 301
 302         /* Get list header so we know how much we'll receive. */
 303         ret = recv_reply(app->sock, &reply_hdr, sizeof(reply_hdr));
 304         if (ret < 0) {
 305                 goto error_io;
 306         }
 307
 308         reply_ret_code = be32toh(reply_hdr.ret_code);
 309         log_reply_code(reply_ret_code);
 310         switch (reply_ret_code) {
 311         case AGENT_RET_CODE_SUCCESS:
 312                 data_size = be32toh(reply_hdr.data_size) + sizeof(*reply);
 313                 break;
 314         default:
 315                 ret = LTTNG_ERR_UNK;
 316                 goto error;
 317         }
 318
 319         reply = zmalloc(data_size);
 320         if (!reply) {
 321                 ret = LTTNG_ERR_NOMEM;
 322                 goto error;
 323         }
 324
 325         /* Get the list with the appropriate data size. */
 326         ret = recv_reply(app->sock, reply, data_size);
 327         if (ret < 0) {
 328                 goto error_io;
 329         }
 330
 331         nb_event = be32toh(reply->nb_event);
 332         tmp_events = zmalloc(sizeof(*tmp_events) * nb_event);
 333         if (!tmp_events) {
 334                 ret = LTTNG_ERR_NOMEM;
 335                 goto error;
 336         }
 337
 338         for (i = 0; i < nb_event; i++) {
 339                 offset += len;
 340                 strncpy(tmp_events[i].name, reply->payload + offset,
 341                                 sizeof(tmp_events[i].name));
 342                 tmp_events[i].pid = app->pid;
 343                 tmp_events[i].enabled = -1;
 344                 len = strlen(reply->payload + offset) + 1;
 345         }
 346
 347         *events = tmp_events;
 348
 349         free(reply);
 350         return nb_event;
 351
 352 error_io:
 353         ret = LTTNG_ERR_UST_LIST_FAIL;
 354 error:
 355         free(reply);
 356         free(tmp_events);
 357         return -ret;
 358
 359 }
 360
 361 /*
 362  * Internal enable agent event on a agent application. This function
 363  * communicates with the agent to enable a given event.
 364  *
 365  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 366  */
 367 static int enable_event(struct agent_app *app, struct agent_event *event)
 368 {
 369         int ret;
 370         char *bytes_to_send;
 371         uint64_t data_size;
 372         size_t filter_expression_length;
 373         uint32_t reply_ret_code;
 374         struct lttcomm_agent_enable msg;
 375         struct lttcomm_agent_generic_reply reply;
 376
 377         assert(app);
 378         assert(app->sock);
 379         assert(event);
 380
 381         DBG2("Agent enabling event %s for app pid: %d and socket %d", event->name,
 382                         app->pid, app->sock->fd);
 383
 384         /*
 385          * Calculate the payload's size, which is the fixed-size struct followed
 386          * by the variable-length filter expression (+1 for the ending \0).
 387          */
 388         if (!event->filter_expression) {
 389                 filter_expression_length = 0;
 390         } else {
 391                 filter_expression_length = strlen(event->filter_expression) + 1;
 392         }
 393         data_size = sizeof(msg) + filter_expression_length;
 394
 395         ret = send_header(app->sock, data_size, AGENT_CMD_ENABLE, 0);
 396         if (ret < 0) {
 397                 goto error_io;
 398         }
 399
 400         memset(&msg, 0, sizeof(msg));
 401         msg.loglevel_value = event->loglevel_value;
 402         msg.loglevel_type = event->loglevel_type;
 403         strncpy(msg.name, event->name, sizeof(msg.name));
 404         msg.filter_expression_length = filter_expression_length;
 405
 406         bytes_to_send = zmalloc(data_size);
 407         if (!bytes_to_send) {
 408                 ret = LTTNG_ERR_NOMEM;
 409                 goto error;
 410         }
 411
 412         memcpy(bytes_to_send, &msg, sizeof(msg));
 413         if (filter_expression_length > 0) {
 414                 memcpy(bytes_to_send + sizeof(msg), event->filter_expression,
 415                                 filter_expression_length);
 416         }
 417
 418         ret = send_payload(app->sock, bytes_to_send, data_size);
 419         free(bytes_to_send);
 420         if (ret < 0) {
 421                 goto error_io;
 422         }
 423
 424         ret = recv_reply(app->sock, &reply, sizeof(reply));
 425         if (ret < 0) {
 426                 goto error_io;
 427         }
 428
 429         reply_ret_code = be32toh(reply.ret_code);
 430         log_reply_code(reply_ret_code);
 431         switch (reply_ret_code) {
 432         case AGENT_RET_CODE_SUCCESS:
 433                 break;
 434         case AGENT_RET_CODE_UNKNOWN_NAME:
 435                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 436                 goto error;
 437         default:
 438                 ret = LTTNG_ERR_UNK;
 439                 goto error;
 440         }
 441
 442         return LTTNG_OK;
 443
 444 error_io:
 445         ret = LTTNG_ERR_UST_ENABLE_FAIL;
 446 error:
 447         return ret;
 448 }
 449
 450 /*
 451  * Internal disable agent event call on a agent application. This function
 452  * communicates with the agent to disable a given event.
 453  *
 454  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 455  */
 456 static int disable_event(struct agent_app *app, struct agent_event *event)
 457 {
 458         int ret;
 459         uint64_t data_size;
 460         uint32_t reply_ret_code;
 461         struct lttcomm_agent_disable msg;
 462         struct lttcomm_agent_generic_reply reply;
 463
 464         assert(app);
 465         assert(app->sock);
 466         assert(event);
 467
 468         DBG2("Agent disabling event %s for app pid: %d and socket %d", event->name,
 469                         app->pid, app->sock->fd);
 470
 471         data_size = sizeof(msg);
 472
 473         ret = send_header(app->sock, data_size, AGENT_CMD_DISABLE, 0);
 474         if (ret < 0) {
 475                 goto error_io;
 476         }
 477
 478         memset(&msg, 0, sizeof(msg));
 479         strncpy(msg.name, event->name, sizeof(msg.name));
 480         ret = send_payload(app->sock, &msg, sizeof(msg));
 481         if (ret < 0) {
 482                 goto error_io;
 483         }
 484
 485         ret = recv_reply(app->sock, &reply, sizeof(reply));
 486         if (ret < 0) {
 487                 goto error_io;
 488         }
 489
 490         reply_ret_code = be32toh(reply.ret_code);
 491         log_reply_code(reply_ret_code);
 492         switch (reply_ret_code) {
 493         case AGENT_RET_CODE_SUCCESS:
 494                 break;
 495         case AGENT_RET_CODE_UNKNOWN_NAME:
 496                 ret = LTTNG_ERR_UST_EVENT_NOT_FOUND;
 497                 goto error;
 498         default:
 499                 ret = LTTNG_ERR_UNK;
 500                 goto error;
 501         }
 502
 503         return LTTNG_OK;
 504
 505 error_io:
 506         ret = LTTNG_ERR_UST_DISABLE_FAIL;
 507 error:
 508         return ret;
 509 }
 510
 511 /*
 512  * Send back the registration DONE command to a given agent application.
 513  *
 514  * Return 0 on success or else a negative value.
 515  */
 516 int agent_send_registration_done(struct agent_app *app)
 517 {
 518         assert(app);
 519         assert(app->sock);
 520
 521         DBG("Agent sending registration done to app socket %d", app->sock->fd);
 522
 523         return send_header(app->sock, 0, AGENT_CMD_REG_DONE, 0);
 524 }
 525
 526 /*
 527  * Enable agent event on every agent applications registered with the session
 528  * daemon.
 529  *
 530  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 531  */
 532 int agent_enable_event(struct agent_event *event,
 533                 enum lttng_domain_type domain)
 534 {
 535         int ret;
 536         struct agent_app *app;
 537         struct lttng_ht_iter iter;
 538
 539         assert(event);
 540
 541         rcu_read_lock();
 542
 543         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 544                         node.node) {
 545                 if (app->domain != domain) {
 546                         continue;
 547                 }
 548
 549                 /* Enable event on agent application through TCP socket. */
 550                 ret = enable_event(app, event);
 551                 if (ret != LTTNG_OK) {
 552                         goto error;
 553                 }
 554         }
 555
 556         event->enabled = 1;
 557         ret = LTTNG_OK;
 558
 559 error:
 560         rcu_read_unlock();
 561         return ret;
 562 }
 563
 564 /*
 565  * Disable agent event on every agent applications registered with the session
 566  * daemon.
 567  *
 568  * Return LTTNG_OK on success or else a LTTNG_ERR* code.
 569  */
 570 int agent_disable_event(struct agent_event *event,
 571                 enum lttng_domain_type domain)
 572 {
 573         int ret = LTTNG_OK;
 574         struct agent_app *app;
 575         struct lttng_ht_iter iter;
 576
 577         assert(event);
 578         if (!event->enabled) {
 579                 goto end;
 580         }
 581
 582         rcu_read_lock();
 583
 584         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 585                         node.node) {
 586                 if (app->domain != domain) {
 587                         continue;
 588                 }
 589
 590                 /* Enable event on agent application through TCP socket. */
 591                 ret = disable_event(app, event);
 592                 if (ret != LTTNG_OK) {
 593                         goto error;
 594                 }
 595         }
 596
 597         event->enabled = 0;
 598
 599 error:
 600         rcu_read_unlock();
 601 end:
 602         return ret;
 603 }
 604
 605 /*
 606  * Ask every agent for the list of possible event. Events is allocated with the
 607  * events of every agent application.
 608  *
 609  * Return the number of events or else a negative value.
 610  */
 611 int agent_list_events(struct lttng_event **events,
 612                 enum lttng_domain_type domain)
 613 {
 614         int ret;
 615         size_t nbmem, count = 0;
 616         struct agent_app *app;
 617         struct lttng_event *tmp_events = NULL;
 618         struct lttng_ht_iter iter;
 619
 620         assert(events);
 621
 622         DBG2("Agent listing events for domain %d", domain);
 623
 624         nbmem = UST_APP_EVENT_LIST_SIZE;
 625         tmp_events = zmalloc(nbmem * sizeof(*tmp_events));
 626         if (!tmp_events) {
 627                 PERROR("zmalloc agent list events");
 628                 ret = -ENOMEM;
 629                 goto error;
 630         }
 631
 632         rcu_read_lock();
 633         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, app,
 634                         node.node) {
 635                 ssize_t nb_ev;
 636                 struct lttng_event *agent_events;
 637
 638                 /* Skip domain not asked by the list. */
 639                 if (app->domain != domain) {
 640                         continue;
 641                 }
 642
 643                 nb_ev = list_events(app, &agent_events);
 644                 if (nb_ev < 0) {
 645                         ret = nb_ev;
 646                         goto error_unlock;
 647                 }
 648
 649                 if (count + nb_ev > nbmem) {
 650                         /* In case the realloc fails, we free the memory */
 651                         struct lttng_event *new_tmp_events;
 652                         size_t new_nbmem;
 653
 654                         new_nbmem = max_t(size_t, count + nb_ev, nbmem << 1);
 655                         DBG2("Reallocating agent event list from %zu to %zu entries",
 656                                         nbmem, new_nbmem);
 657                         new_tmp_events = realloc(tmp_events,
 658                                 new_nbmem * sizeof(*new_tmp_events));
 659                         if (!new_tmp_events) {
 660                                 PERROR("realloc agent events");
 661                                 ret = -ENOMEM;
 662                                 free(agent_events);
 663                                 goto error_unlock;
 664                         }
 665                         /* Zero the new memory */
 666                         memset(new_tmp_events + nbmem, 0,
 667                                 (new_nbmem - nbmem) * sizeof(*new_tmp_events));
 668                         nbmem = new_nbmem;
 669                         tmp_events = new_tmp_events;
 670                 }
 671                 memcpy(tmp_events + count, agent_events,
 672                         nb_ev * sizeof(*tmp_events));
 673                 free(agent_events);
 674                 count += nb_ev;
 675         }
 676         rcu_read_unlock();
 677
 678         ret = count;
 679         *events = tmp_events;
 680         return ret;
 681
 682 error_unlock:
 683         rcu_read_unlock();
 684 error:
 685         free(tmp_events);
 686         return ret;
 687 }
 688
 689 /*
 690  * Create a agent app object using the given PID.
 691  *
 692  * Return newly allocated object or else NULL on error.
 693  */
 694 struct agent_app *agent_create_app(pid_t pid, enum lttng_domain_type domain,
 695                 struct lttcomm_sock *sock)
 696 {
 697         struct agent_app *app;
 698
 699         assert(sock);
 700
 701         app = zmalloc(sizeof(*app));
 702         if (!app) {
 703                 PERROR("zmalloc agent create");
 704                 goto error;
 705         }
 706
 707         app->pid = pid;
 708         app->domain = domain;
 709         app->sock = sock;
 710         lttng_ht_node_init_ulong(&app->node, (unsigned long) app->sock->fd);
 711
 712 error:
 713         return app;
 714 }
 715
 716 /*
 717  * Lookup agent app by socket in the global hash table.
 718  *
 719  * RCU read side lock MUST be acquired.
 720  *
 721  * Return object if found else NULL.
 722  */
 723 struct agent_app *agent_find_app_by_sock(int sock)
 724 {
 725         struct lttng_ht_node_ulong *node;
 726         struct lttng_ht_iter iter;
 727         struct agent_app *app;
 728
 729         assert(sock >= 0);
 730
 731         lttng_ht_lookup(agent_apps_ht_by_sock, (void *)((unsigned long) sock), &iter);
 732         node = lttng_ht_iter_get_node_ulong(&iter);
 733         if (node == NULL) {
 734                 goto error;
 735         }
 736         app = caa_container_of(node, struct agent_app, node);
 737
 738         DBG3("Agent app pid %d found by sock %d.", app->pid, sock);
 739         return app;
 740
 741 error:
 742         DBG3("Agent app NOT found by sock %d.", sock);
 743         return NULL;
 744 }
 745
 746 /*
 747  * Add agent application object to the global hash table.
 748  */
 749 void agent_add_app(struct agent_app *app)
 750 {
 751         assert(app);
 752
 753         DBG3("Agent adding app sock: %d and pid: %d to ht", app->sock->fd, app->pid);
 754         lttng_ht_add_unique_ulong(agent_apps_ht_by_sock, &app->node);
 755 }
 756
 757 /*
 758  * Delete agent application from the global hash table.
 759  *
 760  * rcu_read_lock() must be held by the caller.
 761  */
 762 void agent_delete_app(struct agent_app *app)
 763 {
 764         int ret;
 765         struct lttng_ht_iter iter;
 766
 767         assert(app);
 768
 769         DBG3("Agent deleting app pid: %d and sock: %d", app->pid, app->sock->fd);
 770
 771         iter.iter.node = &app->node.node;
 772         ret = lttng_ht_del(agent_apps_ht_by_sock, &iter);
 773         assert(!ret);
 774 }
 775
 776 /*
 777  * Destroy an agent application object by detaching it from its corresponding
 778  * UST app if one is connected by closing the socket. Finally, perform a
 779  * delayed memory reclaim.
 780  */
 781 void agent_destroy_app(struct agent_app *app)
 782 {
 783         assert(app);
 784
 785         if (app->sock) {
 786                 app->sock->ops->close(app->sock);
 787                 lttcomm_destroy_sock(app->sock);
 788         }
 789
 790         call_rcu(&app->node.head, destroy_app_agent_rcu);
 791 }
 792
 793 /*
 794  * Initialize an already allocated agent object.
 795  *
 796  * Return 0 on success or else a negative errno value.
 797  */
 798 int agent_init(struct agent *agt)
 799 {
 800         int ret;
 801
 802         assert(agt);
 803
 804         agt->events = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 805         if (!agt->events) {
 806                 ret = -ENOMEM;
 807                 goto error;
 808         }
 809         lttng_ht_node_init_u64(&agt->node, agt->domain);
 810
 811         return 0;
 812
 813 error:
 814         return ret;
 815 }
 816
 817 /*
 818  * Add agent object to the given hash table.
 819  */
 820 void agent_add(struct agent *agt, struct lttng_ht *ht)
 821 {
 822         assert(agt);
 823         assert(ht);
 824
 825         DBG3("Agent adding from domain %d", agt->domain);
 826
 827         lttng_ht_add_unique_u64(ht, &agt->node);
 828 }
 829
 830 /*
 831  * Create an agent object for the given domain.
 832  *
 833  * Return the allocated agent or NULL on error.
 834  */
 835 struct agent *agent_create(enum lttng_domain_type domain)
 836 {
 837         int ret;
 838         struct agent *agt;
 839
 840         agt = zmalloc(sizeof(struct agent));
 841         if (!agt) {
 842                 goto error;
 843         }
 844         agt->domain = domain;
 845
 846         ret = agent_init(agt);
 847         if (ret < 0) {
 848                 free(agt);
 849                 agt = NULL;
 850                 goto error;
 851         }
 852
 853 error:
 854         return agt;
 855 }
 856
 857 /*
 858  * Create a newly allocated agent event data structure.
 859  * Ownership of filter_expression is taken.
 860  *
 861  * Return a new object else NULL on error.
 862  */
 863 struct agent_event *agent_create_event(const char *name,
 864                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 865                 struct lttng_filter_bytecode *filter, char *filter_expression)
 866 {
 867         struct agent_event *event = NULL;
 868
 869         DBG3("Agent create new event with name %s, loglevel type %d, \
 870                         loglevel value %d and filter %s",
 871                         name, loglevel_type, loglevel_value, filter_expression);
 872
 873         if (!name) {
 874                 ERR("Failed to create agent event; no name provided.");
 875                 goto error;
 876         }
 877
 878         event = zmalloc(sizeof(*event));
 879         if (!event) {
 880                 goto error;
 881         }
 882
 883         strncpy(event->name, name, sizeof(event->name));
 884         event->name[sizeof(event->name) - 1] = '\0';
 885         lttng_ht_node_init_str(&event->node, event->name);
 886
 887         event->loglevel_value = loglevel_value;
 888         event->loglevel_type = loglevel_type;
 889         event->filter = filter;
 890         event->filter_expression = filter_expression;
 891 error:
 892         return event;
 893 }
 894
 895 /*
 896  * Unique add of a agent event to an agent object.
 897  */
 898 void agent_add_event(struct agent_event *event, struct agent *agt)
 899 {
 900         assert(event);
 901         assert(agt);
 902         assert(agt->events);
 903
 904         DBG3("Agent adding event %s", event->name);
 905         add_unique_agent_event(agt->events, event);
 906         agt->being_used = 1;
 907 }
 908
 909 /*
 910  * Find multiple agent events sharing the given name.
 911  *
 912  * RCU read side lock MUST be acquired. It must be held for the
 913  * duration of the iteration.
 914  *
 915  * Sets the given iterator.
 916  */
 917 void agent_find_events_by_name(const char *name, struct agent *agt,
 918                 struct lttng_ht_iter* iter)
 919 {
 920         struct lttng_ht *ht;
 921         struct agent_ht_key key;
 922
 923         assert(name);
 924         assert(agt);
 925         assert(agt->events);
 926         assert(iter);
 927
 928         ht = agt->events;
 929         key.name = name;
 930
 931         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 932                         ht_match_event_by_name, &key, &iter->iter);
 933 }
 934
 935 /*
 936  * Get the next agent event duplicate by name. This should be called
 937  * after a call to agent_find_events_by_name() to iterate on events.
 938  *
 939  * The RCU read lock must be held during the iteration and for as long
 940  * as the object the iterator points to remains in use.
 941  */
 942 void agent_event_next_duplicate(const char *name,
 943                 struct agent *agt, struct lttng_ht_iter* iter)
 944 {
 945         struct agent_ht_key key;
 946
 947         key.name = name;
 948
 949         cds_lfht_next_duplicate(agt->events->ht, ht_match_event_by_name,
 950                 &key, &iter->iter);
 951 }
 952
 953 /*
 954  * Find a agent event in the given agent using name, loglevel and filter.
 955  *
 956  * RCU read side lock MUST be acquired. It must be kept for as long as
 957  * the returned agent_event is used.
 958  *
 959  * Return object if found else NULL.
 960  */
 961 struct agent_event *agent_find_event(const char *name,
 962                 enum lttng_loglevel_type loglevel_type, int loglevel_value,
 963                 char *filter_expression, struct agent *agt)
 964 {
 965         struct lttng_ht_node_str *node;
 966         struct lttng_ht_iter iter;
 967         struct lttng_ht *ht;
 968         struct agent_ht_key key;
 969
 970         assert(name);
 971         assert(agt);
 972         assert(agt->events);
 973
 974         ht = agt->events;
 975         key.name = name;
 976         key.loglevel_value = loglevel_value;
 977         key.loglevel_type = loglevel_type;
 978         key.filter_expression = filter_expression;
 979
 980         cds_lfht_lookup(ht->ht, ht->hash_fct((void *) name, lttng_ht_seed),
 981                         ht_match_event, &key, &iter.iter);
 982         node = lttng_ht_iter_get_node_str(&iter);
 983         if (node == NULL) {
 984                 goto error;
 985         }
 986
 987         DBG3("Agent event found %s.", name);
 988         return caa_container_of(node, struct agent_event, node);
 989
 990 error:
 991         DBG3("Agent event NOT found %s.", name);
 992         return NULL;
 993 }
 994
 995 /*
 996  * Free given agent event. This event must not be globally visible at this
 997  * point (only expected to be used on failure just after event creation). After
 998  * this call, the pointer is not usable anymore.
 999  */
1000 void agent_destroy_event(struct agent_event *event)
1001 {
1002         assert(event);
1003
1004         free(event->filter);
1005         free(event->filter_expression);
1006         free(event->exclusion);
1007         free(event);
1008 }
1009
1010 /*
1011  * Destroy an agent completely.
1012  */
1013 void agent_destroy(struct agent *agt)
1014 {
1015         struct lttng_ht_node_str *node;
1016         struct lttng_ht_iter iter;
1017
1018         assert(agt);
1019
1020         DBG3("Agent destroy");
1021
1022         rcu_read_lock();
1023         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, node, node) {
1024                 int ret;
1025                 struct agent_event *event;
1026
1027                 /*
1028                  * When destroying an event, we have to try to disable it on the agent
1029                  * side so the event stops generating data. The return value is not
1030                  * important since we have to continue anyway destroying the object.
1031                  */
1032                 event = caa_container_of(node, struct agent_event, node);
1033                 (void) agent_disable_event(event, agt->domain);
1034
1035                 ret = lttng_ht_del(agt->events, &iter);
1036                 assert(!ret);
1037                 call_rcu(&node->head, destroy_event_agent_rcu);
1038         }
1039         rcu_read_unlock();
1040
1041         ht_cleanup_push(agt->events);
1042         free(agt);
1043 }
1044
1045 /*
1046  * Allocate agent_apps_ht_by_sock.
1047  */
1048 int agent_app_ht_alloc(void)
1049 {
1050         int ret = 0;
1051
1052         agent_apps_ht_by_sock = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
1053         if (!agent_apps_ht_by_sock) {
1054                 ret = -1;
1055         }
1056
1057         return ret;
1058 }
1059
1060 /*
1061  * Destroy a agent application by socket.
1062  */
1063 void agent_destroy_app_by_sock(int sock)
1064 {
1065         struct agent_app *app;
1066
1067         assert(sock >= 0);
1068
1069         /*
1070          * Not finding an application is a very important error that should NEVER
1071          * happen. The hash table deletion is ONLY done through this call when the
1072          * main sessiond thread is torn down.
1073          */
1074         rcu_read_lock();
1075         app = agent_find_app_by_sock(sock);
1076         assert(app);
1077
1078         /* RCU read side lock is assumed to be held by this function. */
1079         agent_delete_app(app);
1080
1081         /* The application is freed in a RCU call but the socket is closed here. */
1082         agent_destroy_app(app);
1083         rcu_read_unlock();
1084 }
1085
1086 /*
1087  * Clean-up the agent app hash table and destroy it.
1088  */
1089 void agent_app_ht_clean(void)
1090 {
1091         struct lttng_ht_node_ulong *node;
1092         struct lttng_ht_iter iter;
1093
1094         if (!agent_apps_ht_by_sock) {
1095                 return;
1096         }
1097         rcu_read_lock();
1098         cds_lfht_for_each_entry(agent_apps_ht_by_sock->ht, &iter.iter, node, node) {
1099                 struct agent_app *app;
1100
1101                 app = caa_container_of(node, struct agent_app, node);
1102                 agent_destroy_app_by_sock(app->sock->fd);
1103         }
1104         rcu_read_unlock();
1105
1106         lttng_ht_destroy(agent_apps_ht_by_sock);
1107 }
1108
1109 /*
1110  * Update a agent application (given socket) using the given agent.
1111  *
1112  * Note that this function is most likely to be used with a tracing session
1113  * thus the caller should make sure to hold the appropriate lock(s).
1114  */
1115 void agent_update(struct agent *agt, int sock)
1116 {
1117         int ret;
1118         struct agent_app *app;
1119         struct agent_event *event;
1120         struct lttng_ht_iter iter;
1121
1122         assert(agt);
1123         assert(sock >= 0);
1124
1125         DBG("Agent updating app socket %d", sock);
1126
1127         rcu_read_lock();
1128         cds_lfht_for_each_entry(agt->events->ht, &iter.iter, event, node.node) {
1129                 /* Skip event if disabled. */
1130                 if (!event->enabled) {
1131                         continue;
1132                 }
1133
1134                 app = agent_find_app_by_sock(sock);
1135                 /*
1136                  * We are in the registration path thus if the application is gone,
1137                  * there is a serious code flow error.
1138                  */
1139                 assert(app);
1140
1141                 ret = enable_event(app, event);
1142                 if (ret != LTTNG_OK) {
1143                         DBG2("Agent update unable to enable event %s on app pid: %d sock %d",
1144                                         event->name, app->pid, app->sock->fd);
1145                         /* Let's try the others here and don't assume the app is dead. */
1146                         continue;
1147                 }
1148         }
1149         rcu_read_unlock();
1150 }